Thanks for the quick help. Sorry I sent the first answer not to the mailing list, because I just used the reply funcion.
Unfortunatley the mails are not spam and the like to receive them. We've tracked down the problem to a second mail-server that the problem mails passed withing the infrastructure of our mail provider. Each mail that has passed that second station got the problem with the wrong return-path set. Mails that passes only one station within our mail provider do not have that problem. Somtimes two mailes from our customers that come directly after each other differ only in that, one of them reached the two stations within our mail provider and got the invalid return path. The other is fully ok. We've already tried and try to get support from our mail provider, but we haven't reached someone at the support yet, that fully understands our problem and can help us. -----Ursprüngliche Nachricht----- Gesendet: Donnerstag, 13 Februar 2014 um 11:16:35 Uhr Von: "Mark Goodge" <m...@good-stuff.co.uk> An: postfix-users@postfix.org Betreff: Re: Entries in sender_bcc_maps and the return-path header On 13/02/2014 09:46, template.mob...@gmx.de wrote: > Hi, > > i'm using postfix in our small company successfully for many years. > But now a problem arised and I was not able to solve it myself or > with help from the docs. > > We are using sender_bcc_maps, because we want any mail that is sent > from one of our employees to be copied to a central mail account. > Since a few month our mail provider delivers us mails that are > addressed to one of our employees, where the return-path header ist > set to the mail address of the receiving employee. The mail is now > copied to our central outgoing account. We don't want that. Well, setting the return path header to be the same as the recipient is wrong, and stupid. So if this is being done by your mail provider then you need to complain to them, raising a fault report if necessary (because this is a fault, and a serious one), in order to get the problem resolved. But it's also possible that it's being done by the original sender of the email, in which case the chances are that it's simply spam, since this is a common trick of spammers to try to get round filters. > How does the sender_bcc_maps mechanism exactly works? Does it react > on mail body header fields like return-path? Is it in detailed > documented somewhere? Can we prevent sender_bcc_maps from reacting on > the return-path field? http://www.postfix.org/postconf.5.html lists the order in which Postfix determines the sender for the purposes of bcc_sender_maps: 1. Look up the "user+extens...@domain.tld" address including the optional address extension. 2. Look up the "u...@domain.tld" address without the optional address extension. 3. Look up the "user+extension" address local part when the sender domain equals $myorigin, $mydestination, $inet_interfaces or $proxy_interfaces. 4. Look up the "user" address local part when the sender domain equals $myorigin, $mydestination, $inet_interfaces or $proxy_interfaces. 5. Look up the "@domain.tld" part. > If not, how can our problem be solved? Should we use some kind of > filter for incoming mails that removes the return-path? If it isn't being caused by a fault at your mail provider, then I'd be inclined to simply reject anything where the sender or return path address is the same as the recipient. The chances are greater than 99% that it's spam. And if it isn't, someone sending mail out that's so badly configured doesn't deserve to have it delivered. Mark -- My blog: http://mark.goodge.co.uk
